Display device using semiconductor light emitting diode

ABSTRACT

Discussed is a display device using a semiconductor light emitting diode disposed on a substrate, a planarization layer stacked on the substrate while defining a hole that is a region in which the semiconductor light emitting diode is disposed, a light-transmitting layer filling the hole, and a reflective layer formed along at least one surface of the substrate and the planarization layer defining an inner surface of the hole, wherein the hole is formed so that a width thereof expands as a distance from the substrate increases.

TECHNICAL FIELD

The present disclosure relates to a display device, and moreparticularly, to a display device using a semiconductor light emittingdiode having a size of several μm to several tens of μm.

BACKGROUND ART

Recently, in the field of display technology, display devices withexcellent characteristics, such as thin film display devices andflexible display devices, are under development. On the other hand,representative currently commercialized major displays are liquidcrystal display (LCD) and active matrix organic light emitting diode(AMOLED). However, the LCD has disadvantages in terms of slow responsetime and difficult implementation of flexibility, and the AMOLED hasweaknesses in terms of short lifespan and production yield.

On the other hand, light emitting diodes (LEDs) are semiconductor lightemitting diodes widely known to convert electric current into light.Starting with the commercialization of red LEDs using a GaAsP compoundsemiconductor in 1962, the LEDs have been used as a light source fordisplay images of electronic devices, including information andcommunication devices, along with GaP:N-based green LEDs. If thesemiconductor light emitting diodes are used to implement displaydevices, a method for solving the above-described problem may beproposed.

In this regard, recently, research and development has been conductedinto display devices using micro-LEDs. Since such display devices havehigh image quality and high reliability, such display devices attractattention as a next-generation display.

However, a conventional display device using a micro-LED has a structurein which the micro-LED emitting light is surrounded by a transparentlayer, and light loss occurs in the rear and side surfaces of a panel,which deteriorates image quality of the display device.

DISCLOSURE OF INVENTION Technical Problem

Embodiments of the present disclosure provide a display device using asemiconductor light emitting diode having a structure capable ofefficiently collecting light emitted from the semiconductor lightemitting diode to a front surface of a panel.

Technical Solution

A display device according to an embodiment of the present disclosureincludes a substrate, a semiconductor light emitting diode disposed onthe substrate, a planarization layer stacked on the substrate whiledefining a hole that is a region in which the semiconductor lightemitting diode is disposed, a light-transmitting layer filling the hole,and a reflective layer formed along at least one surface of thesubstrate and the planarization layer defining an inner surface of thehole, wherein the hole may be formed so that a width thereof expands asa distance from the substrate increases.

In the present embodiment, a cross-sectional shape of the hole cut in aplane perpendicular to the substrate may have a bilaterally symmetricalstructure.

In the present embodiment, the hole may include a plurality of regionspartitioned based on an arbitrary height, wherein thicknesses of therespective regions in a height direction may be equal to each other, ora thickness of at least one of the plurality of regions in the heightdirection may be different from a thickness of another region in theheight direction.

In the present embodiment, the planarization layer may be inclined in adirection to expand the width of the hole as the distance from thesubstrate increases.

In the present embodiment, the hole may include a plurality of regionspartitioned based on an arbitrary height, wherein slopes of theplanarization layer included in the respective regions with respect tothe substrate or an imaginary plane parallel to the substrate may beequal to each other, or a slope of the planarization layer included inat least one of the plurality of regions with respect to the substrateor the imaginary plane parallel to the substrate may be different from aslope of the planarization layer included in another region.

In the present embodiment, the planarization layer may include aplurality of layers stacked in a height direction of the hole, and atleast adjacent layers may be made of different materials.

In the present embodiment, the reflective layer may be formed so that aportion formed along one surface of the substrate among the innersurfaces of the hole is thicker than a portion formed along one surfaceof the planarization layer.

In the present embodiment, the reflective layer may further include afirst portion extending along at least a portion of an interface betweenthe substrate and the planarization layer.

In the present embodiment, the reflective layer may further include asecond portion extending to cover at least a portion of an upper surfaceof the planarization layer.

In the present embodiment, the reflective layer may include a metal thinfilm layer having a single-layered or multi-layered structure, whereinthe metal thin film layer may be made of one of titanium (Ti), aluminum(Al), silver (Ag), chromium (Cr), molybdenum (Mo), and platinum (Pt), orany combination thereof, and may be formed to a thickness of at least 30nm or more.

In the present embodiment, the reflective layer may further include aprotective layer made of SiO₂ or SiN_(x) on the metal thin film layer.

In the present embodiment, the hole may have a circular horizontalcross-section.

In the present embodiment, the display device may further include ablack matrix (BM) on an upper surface of the planarization layer.

Advantageous Effects

A display device using a semiconductor light emitting diode according toan embodiment of the present disclosure has an effect of efficientlycollecting light emitted from the semiconductor light emitting diode toa front surface of a panel due to the shape and structuralcharacteristics of a hole in which the semiconductor light emittingdiode is disposed.

Specifically, a reflective layer formed along the inner surface of thehole can reflect light leaking through the side or rear surface of thesemiconductor light emitting diode toward the front surface of thepanel, and the structure of the hole in which the width increases as adistance from a substrate increases and the vertical cross-section issymmetrical has an effect of improving the light collection efficiency.

In addition, the present disclosure has an effect of maximizing thelight collection efficiency by applying the structure of the holechanged according to the shape, thickness, structure, and the like ofthe semiconductor light emitting diode disposed inside the hole.

Furthermore, since a first portion and/or a second portion extendingfrom the reflective layer formed on the inner surface of the hole areincluded, the present disclosure has an effect of maintaining the lightcollection efficiency by supplementing the positional precision in aprocess of assembling the semiconductor light emitting diode.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a conceptual diagram showing a display device using asemiconductor light emitting diode according to an embodiment of thepresent disclosure.

FIG. 2 is a partial enlarged view of portion A of FIG. 1, and FIGS. 3aand 3b are cross-sectional views taken along lines B-B and C-C of FIG.2, respectively.

FIG. 4 is a conceptual diagram showing a flip-chip type semiconductorlight emitting diode of FIG. 3.

FIGS. 5a to 5c are conceptual diagrams showing various forms ofimplementing color in relation to the flip-chip type semiconductor lightemitting diode.

FIG. 6 is a cross-sectional view showing a method of manufacturing adisplay device using a semiconductor light emitting diode according tothe present disclosure.

FIG. 7 is a perspective view showing a display device using asemiconductor light emitting diode according to another embodiment ofthe present disclosure.

FIG. 8 is a cross-sectional view taken along line D-D of FIG. 7.

FIG. 9 is a conceptual diagram showing a vertical semiconductor lightemitting diode of FIG. 8.

FIG. 10 is a view showing a vertical cross-section of a hole in whichthe semiconductor light emitting diode is disposed, according to anembodiment of the present disclosure.

FIG. 11 is a view showing a vertical cross-section of a hole in whichthe semiconductor light emitting diode is disposed, according to anotherembodiment of the present disclosure.

FIGS. 12a to 12e are views showing various embodiments of the hole shownin FIG. 11.

FIG. 13 is a view showing problems that may occur in a reflective layerstructure according to an embodiment of the present disclosure.

FIG. 14 is a view showing a structure of a reflective layer according toan embodiment of the present disclosure.

MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present disclosure are described indetail with reference to accompanying drawings and regardless of thereference symbols, same or similar components are assigned with the samereference numerals and thus overlapping descriptions for those areomitted. The suffixes “module” and “unit” for components used in thedescription below are assigned or mixed in consideration of easiness inwriting the specification and do not have distinctive meanings or rolesby themselves. In the following description, detailed descriptions ofwell-known functions or constructions will be omitted since they wouldobscure the invention in unnecessary detail. Additionally, theaccompanying drawings are used to help easily understanding embodimentsdisclosed herein but the technical idea of the present disclosure is notlimited thereto. In addition, when an element such as a layer, a region,or a substrate is referred to as being “on” another element, it will beunderstood that the element may be directly on the other element, orintervening elements may be present therebetween.

A display device described in this specification may include a mobilephone, a smart phone, a laptop computer, a digital broadcastingterminal, a personal digital assistant (PDA), a portable multimediaplayer (PMP), a navigation, a slate PC, a tablet PC, an ultra book, adigital TV, a desktop computer, and the like. However, the configurationaccording to embodiments described in this specification can be appliedas long as it can include a display even in a new product form to bedeveloped later.

FIG. 1 is a conceptual diagram showing a display device using asemiconductor light emitting diode according to an embodiment of thepresent disclosure.

As shown, information processed by a controller of a display device 100may be displayed on a flexible display. The flexible display includes adisplay that is flexible, bendable, twistable, foldable, and rollable byexternal force. For example, the flexible display may be a displaymanufactured on a thin and flexible substrate that is flexible,bendable, foldable, or rollable like paper, while maintaining displaycharacteristics of an existing flat panel display.

In a state in which the flexible display is not bent (for example, astate having an infinite radius of curvature, hereinafter referred to asa ‘first state’), the display area of the flexible display is a flatsurface. In a state in which the flexible device is bent by externalforce in the first state (for example, a state having a finite radius ofcurvature, hereinafter referred to as a ‘second state’), the displayarea of the flexible display may be a curved surface. As shown,information displayed in the second state may be visual informationoutput on the curved surface. Such visual information is implemented byindependently controlling light emission of sub-pixels arranged in amatrix form. The sub-pixel refers to a minimum unit for implementing onecolor.

The sub-pixel of the flexible display may be implemented by asemiconductor light emitting diode. In the present disclosure, a lightemitting diode (LED) is exemplified as a type of semiconductor lightemitting diode that converts electric current into light. The LED isformed in a small size, so that the LED can serve as a sub-pixel even inthe second state.

Hereinafter, the flexible display implemented using the LED will bedescribed in more detail with reference to the accompanying drawings.

FIG. 2 is a partial enlarged view of portion A of FIG. 1, FIGS. 3a and3b are cross-sectional views taken along lines B-B and C-C of FIG. 2,respectively, FIG. 4 is a conceptual diagram showing a flip-chip typesemiconductor light emitting diode of FIG. 3, and FIGS. 5a to 5c areconceptual diagrams showing various forms of implementing color inrelation to the flip-chip type semiconductor light emitting diode.

FIGS. 2, 3 a, and 3 b show a display device 100 using a passive matrix(PM) type semiconductor light emitting diode as the display device 100using the semiconductor light emitting diode. However, the followingexample is also applicable to an active matrix (AM) type semiconductorlight emitting diode.

The display device 100 includes a substrate 110, a first electrode 120,a conductive adhesive layer 130, a second electrode 140, and a pluralityof semiconductor light emitting diodes 150.

The substrate 110 may be a flexible substrate. The substrate 110 mayinclude glass or polyimide (PI) in order to implement flexibleperformance. In addition, an insulating and flexible material such aspolyethylene naphthalate (PEN), polyethylene terephthalate (PET), andthe like may be used as the component of the substrate 110. In addition,the substrate 110 may be any transparent material or any opaquematerial.

The substrate 110 may be a wiring substrate on which the first electrode120 is disposed, and the first electrode 120 may be located on thesubstrate 110.

As shown, an insulating layer 160 may be stacked on the substrate 110 onwhich the first electrode 120 is located, and an auxiliary electrode 170may be disposed on the insulating layer 160. In this case, a state inwhich the insulating layer 160 is stacked on the substrate 110 may be asingle wiring substrate. More specifically, the insulating layer 160includes an insulating and flexible material such as PI, PEN, PET, orthe like, and may be integrally formed with the substrate 110 to form asingle wiring substrate.

The auxiliary electrode 170 is an electrode electrically connecting thefirst electrode 120 to the semiconductor light emitting diode 150, andis disposed on the insulating layer 160 and disposed corresponding tothe position of the first electrode 120. For example, the auxiliaryelectrode 170 may have a dot shape and may be electrically connected tothe first electrode 120 via an electrode hole 171 penetrating theinsulating layer 160. The electrode hole 171 may be formed by filling avia hole with a conductive material.

According to the accompanying drawings, the conductive adhesive layer130 is formed on one surface of the insulating layer 160, but thepresent disclosure is not necessarily limited thereto. For example, alayer performing a specific function may be formed between theinsulating layer 160 and the conductive adhesive layer 130, and astructure in which the conductive adhesive layer 130 is disposed on thesubstrate without the insulating layer 160 is also possible. In astructure in which the conductive adhesive layer 130 is disposed on thesubstrate, the conductive adhesive layer 130 may serve as an insulatinglayer.

The conductive adhesive layer 130 may be a layer having adhesiveness andconductivity, to this end, the conductive adhesive layer 130 may beformed by mixing a material having conductivity with a material havingadhesiveness. In addition, the conductive adhesive layer 130 hasductility, thereby enabling a flexible function in the display device.

For example, the conductive adhesive layer 130 may be an anisotropyconductive film (ACF), an anisotropy conductive paste, a solutioncontaining conductive particles, or the like. The conductive adhesivelayer 130 allows electrical interconnection in the z-direction passingthrough the thickness, but may be configured as an electricallyinsulating layer in the horizontal x-y direction. Therefore, theconductive adhesive layer 130 may be referred to as a z-axis conductivelayer (however, hereinafter referred to as a ‘conductive adhesivelayer’).

The anisotropy conductive film is a film in which an anisotropicconductive medium is mixed with an insulating base member, when heat andpressure are applied, the anisotropy conductive film has conductivityonly in a specific portion due to the anisotropic conductive medium. Inthis specification, it is described that heat and pressure are appliedto the anisotropy conductive film, but other methods (for example, amethod of applying only one of heat and pressure or a UV curing method)may be used in order for the anisotropy conductive film to have partialconductivity.

In addition, the anisotropic conductive medium may be conductive ballsor conductive particles. As shown, the anisotropy conductive film is afilm in which conductive balls are mixed with an insulating base member,when heat and pressure are applied, the anisotropy conductive film hasconductivity only in a specific portion due to the conductive balls. Theanisotropy conductive film may be in a state containing particles inwhich a core of a conductive material is coated with an insulating filmmade of a polymer material, in this case, the insulating film of theparticles contained in a portion to which heat and pressure is appliedis destroyed and the anisotropy conductive film has conductivity due tothe core. At this time, the shape of the core may be deformed to formlayers in contact with each other in the thickness direction of thefilm. More specifically, heat and pressure are applied to the entireanisotropy conductive film, and electrical connection in the z-axisdirection may be partially formed due to a height difference of acounterpart adhered by the anisotropy conductive film.

As another example, the anisotropy conductive film may be in a state inwhich an insulating core contains a plurality of particles coated with aconductive material. In this case, the conductive material in theportion to which heat and pressure is applied is deformed (stuck) tohave conductivity in the thickness direction of the film. As anotherexample, the conductive material may penetrate the insulating basemember in the z-axis direction to have conductivity in the thicknessdirection of the film, in this case, the conductive material may have apointed end.

As shown, the anisotropy conductive film may be a fixed array anisotropyconductive film (ACF) in which conductive balls are inserted into onesurface of an insulating base member. The insulating base member is madeof a material having adhesiveness, and the conductive balls areintensively disposed on the bottom portion of the insulating basemember, therefore, when heat and pressure are applied from the basemember, the base member is deformed together with the conductive ball tohave conductivity in the vertical direction.

However, the present disclosure is not necessarily limited thereto, andthe anisotropy conductive film may have a form in which conductive ballsare randomly mixed in an insulating base member, and may be a double-ACFin which a plurality of layers are provided and conductive balls aredisposed on one layer.

The anisotropic conductive paste is a combination of a paste andconductive balls, and may be a paste in which conductive balls are mixedwith an insulating and adhesive base material. In addition, the solutioncontaining conductive particles may be a solution containing conductiveparticles or nanoparticles.

Referring to the accompanying drawings, the second electrode 140 isspaced apart from the auxiliary electrode 170 and is positioned on theinsulating layer 160. That is, the conductive adhesive layer 130 isdisposed on the insulating layer 160 in which the auxiliary electrode170 and the second electrode 140 are located.

After the conductive adhesive layer 130 is formed in a state in whichthe auxiliary electrode 170 and the second electrode 140 are located onthe insulating layer 160, if heat and pressure are applied to connectthe semiconductor light emitting diode 150 in a flip-chip form, thesemiconductor light emitting diode 150 is electrically connected to thefirst electrode 120 and the second electrode 140.

The semiconductor light emitting diode 150 may be a flip-chip type lightemitting diode as shown in FIG. 4.

For example, the semiconductor light emitting diode 150 includes ap-type electrode 156, a p-type semiconductor layer 155 on which thep-type electrode 156 is formed, an active layer 154 formed on the p-typesemiconductor layer 155, an n-type semiconductor layer 153 formed on theactive layer 154, and an n-type electrode 152 spaced apart from thep-type electrode 156 in the horizontal direction on the n-typesemiconductor layer 153. In this case, the p-type electrode 156 may beelectrically connected to the auxiliary electrode 170 by the conductiveadhesive layer 130, and the n-type electrode 152 may be electricallyconnected to the second electrode 140.

Referring to FIGS. 2, 3 a, and 3 b, the auxiliary electrode 170 iselongated in one direction so that one auxiliary electrode 170 may beelectrically connected to the plurality of semiconductor light emittingdiodes 150. For example, the p-type electrodes 156 of the semiconductorlight emitting diodes 150 on the left and right sides of the auxiliaryelectrode 170 may be electrically connected to one auxiliary electrode.

Specifically, the semiconductor light emitting diode 150 is press-fittedinto the conductive adhesive layer 130 by heat and pressure. Therefore,only a portion between the auxiliary electrode 170 and the p-typeelectrode 156 of the semiconductor light emitting diode 150 and aportion between the second electrode 140 and the n-type electrode 152 ofthe semiconductor light emitting diode 150 have conductivity, and theremaining portions have no conductivity because there is nopress-fitting of the semiconductor light emitting diode 150. As such,the conductive adhesive layer 130 may mutually couple and electricallyconnect the semiconductor light emitting diode 150 to the auxiliaryelectrode 170 and may mutually couple and electrically connect thesemiconductor light emitting diode 150 to the second electrode 140.

In addition, the plurality of semiconductor light emitting diodes 150constitute a light emitting diode array, and a phosphor layer 180 isformed in the light emitting diode array.

The light emitting diode array may include the plurality ofsemiconductor light emitting diodes 150 having different luminancevalues. Each of the semiconductor light emitting diodes 150 constitutesa sub-pixel and is electrically connected to the first electrode 120.For example, the first electrode 120 may be provided in plurality. Thesemiconductor light emitting diodes 150 may be arranged in a pluralityof columns. The semiconductor light emitting diodes 150 in each columnmay be electrically connected to any one of the plurality of firstelectrodes 120.

In addition, since the semiconductor light emitting diodes 150 areconnected in a flip-chip form, the semiconductor light emitting diodes150 grown on a transparent dielectric substrate may be used. Thesemiconductor light emitting diodes 150 may be, for example, nitridesemiconductor light emitting diodes. Since the semiconductor lightemitting diodes 150 has excellent luminance, individual sub-pixels canbe configured even with a small size.

Referring to the drawings, partition walls 190 may be formed between thesemiconductor light emitting diodes 150. In this case, the partitionwalls 190 may serve to separate the individual sub-pixels from eachother, and may be integrally formed with the conductive adhesive layer130. For example, since the semiconductor light emitting diode 150 isinserted into the anisotropy conductive film, the base member of theanisotropy conductive film may form the partition wall 190.

In addition, when the base member of the anisotropy conductive film isblack, the partition wall 190 may have reflective properties andincrease contrast even without a separate black insulator.

As another example, a separate reflective partition wall may be providedas the partition wall 190. In this case, the partition wall 190 mayinclude a black or white insulator depending on the purpose of thedisplay device. When the partition wall 190 made of a white insulator isused, there may be an effect of increasing reflectivity, and when thepartition wall 190 made of a black insulator is used, the partition wall190 may have reflective properties and increase contrast.

The phosphor layer 180 may be located on the outer surface of thesemiconductor light emitting diode 150. For example, when thesemiconductor light emitting diode 150 is a blue semiconductor lightemitting diode that emits blue (B) light, the phosphor layer 180 mayperform a function of converting the blue (B) light into a color of asub-pixel. The phosphor layer 180 may be a red phosphor 181 or a greenphosphor 182 constituting an individual pixel.

That is, the red phosphor 181 capable of converting blue (B) light intored (R) light may be stacked on the blue semiconductor light emittingdiode 151 at a position constituting a red sub-pixel, and the greenphosphor 182 capable of converting blue (B) light into green (G) lightmay be stacked on the blue semiconductor light emitting diode 151 at aposition constituting a green sub-pixel. In addition, only the bluesemiconductor light emitting diode 151 may be used alone at the portionconstituting the blue sub-pixel. In this case, red (R), green (G), andblue (B) sub-pixels may constitute one pixel. Specifically, the phosphor180 of one color may be stacked along each line of the first electrode120, and thus, one line in the first electrode 120 may be an electrodethat controls one color. That is, red (R), green (G), and blue (B) maybe sequentially disposed along the second electrode 140, and thesub-pixel may be implemented.

However, the present disclosure is not necessarily limited thereto.Instead of the phosphor 180, the semiconductor light emitting diode 150and quantum dots (QDs) are combined to form red (R), green (G), and blue(B) sub-pixels.

In addition, a black matrix 191 may be disposed between the phosphorlayers 180 in order to improve contrast.

However, the present disclosure is not necessarily limited thereto, andother structures for implementing blue, red, and green colors may beapplied.

Referring to FIG. 5a , each of the semiconductor light emitting diodes150 may be implemented as a high-power light emitting diode that mainlyincludes gallium nitride (GaN) and includes indium (In) and/or aluminum(Al) added together to emit light of various colors including blue.

In this case, the semiconductor light emitting diode 150 may includered, green, and blue semiconductor light emitting diodes in order toconstitute each sub-pixel. For example, red, green, and bluesemiconductor light emitting diodes R, G, and B may be alternatelydisposed, and red, green, and blue sub-pixels may constitute one pixelby the red, green, and blue semiconductor light emitting diodes. In thismanner, a full-color display can be implemented.

Referring to FIG. 5b , the semiconductor light emitting diode 150 may bea white light emitting diode W in which a yellow phosphor layer isprovided for each individual element. In this case, the red phosphorlayer 181, the green phosphor layer 182, and the blue phosphor layer 183may be provided on the white light emitting diode W in order toconstitute the sub-pixel. In addition, the sub-pixel may be formed byusing a color filter in which red, green, and blue are repeated on thewhite light emitting diode W.

Referring to FIG. 5c , the red phosphor layer 181, the green phosphorlayer 182, and the blue phosphor layer 183 may be provided on anultraviolet light emitting diode UV. As such, the semiconductor lightemitting diode 150 can be used in the entire region from the visible rayregion to the ultraviolet ray, and can be extended in the form of asemiconductor light emitting diode in which the ultraviolet ray can beused as the excitation source of the upper phosphor.

Referring back to the present example, the semiconductor light emittingdiode 150 is located on the conductive adhesive layer 130 to constitutethe sub-pixel in the display device. Since the semiconductor lightemitting diodes 150 has excellent luminance, individual sub-pixels canbe configured even with a small size. The size of the individualsemiconductor light emitting diode 150 may be a rectangular or squarediode, of which the size of one side is 80 μm or less. In the case ofthe rectangle diode, the size may be 20×80 μm or less.

In addition, even when the square semiconductor light emitting diode150, of which the size of one side is 10 μm, is used as the sub-pixel,sufficient brightness to achieve the display device may be realized.Therefore, for example, in a case where a rectangular pixel having asub-pixel, of which the size of one side is 600 μm and the size of theother side is 300 μm, the distance between the semiconductor lightemitting diodes 150 is relatively large enough to implement a flexibledisplay device with HD image quality.

The display device using the semiconductor light emitting diodedescribed above can be manufactured by a new manufacturing method.Hereinafter, the manufacturing method will be described with referenceto FIG. 6.

Referring to FIG. 6, a conductive adhesive layer 130 is formed on aninsulating layer 160 on which an auxiliary electrode 170 and a secondelectrode 140 are located. The insulating layer 160 is stacked on afirst substrate 110 to form one substrate (or wiring substrate), and afirst electrode 120, an auxiliary electrode 170, and a second electrode140 are disposed on the wiring substrate. The first electrode 120 andthe second electrode 150 may be disposed in a direction perpendicular toeach other. In addition, in order to implement a flexible displaydevice, each of the first substrate 110 and the insulating layer 160 mayinclude glass or polyimide (PI).

The conductive adhesive layer 130 may be implemented by an anisotropyconductive film. To this end, the anisotropy conductive film may beapplied to the substrate located in the insulating layer 160.

Next, a second substrate 112 on which a plurality of semiconductor lightemitting diodes 150 corresponding to the positions of the auxiliaryelectrodes 170 and the second electrodes 140 and constituting theindividual pixels are located is disposed such that the semiconductorlight emitting diodes 150 face the auxiliary electrodes 170 and thesecond electrodes 140.

In this case, the second substrate 112 is a growth substrate for growingthe semiconductor light emitting diode 150, and may be a sapphiresubstrate or a silicon substrate.

The semiconductor light emitting diode 150 can be effectively used inthe display device because the semiconductor light emitting diode 150has a gap and a size that can form the display device when formed inwafer units.

Next, the wiring substrate and the second substrate 112 arethermocompression-bonded to each other. For example, the wiringsubstrate and the second substrate 112 may be thermocompression-bondedto each other by applying an ACF press head. The wiring substrate andthe second substrate 112 are bonded to each other by thethermocompression bonding. Due to the characteristics of the anisotropyconductive film having conductivity by the thermocompression bonding,only a portion between the semiconductor light emitting diode 150 andthe auxiliary electrode 170 and the second electrode 140 hasconductivity, and the electrodes may be electrically connected to thesemiconductor light emitting diode 150. At this time, the semiconductorlight emitting diode 150 is inserted into the anisotropy conductivefilm. Therefore, partition walls may be formed between the semiconductorlight emitting diodes 150.

Next, the second substrate 112 is removed. For example, the secondsubstrate 112 may be removed using a laser lift-off (LLO) method or achemical lift-off (CLO) method.

Finally, the second substrate 112 is removed to expose the semiconductorlight emitting diode 150 to the outside. If necessary, a transparentinsulating layer (not shown) may be formed by coating the wiringsubstrate, to which the semiconductor light emitting diode 150 iscoupled, with silicon oxide (SiOx) or the like.

In addition, the manufacturing method may further include forming aphosphor layer on one surface of the semiconductor light emitting diode150. For example, the semiconductor light emitting diode 150 is a bluesemiconductor light emitting diode that emits blue (B) light, A redphosphor or a green phosphor for converting the blue (B) light into thecolor of the sub-pixel may form a layer on one surface of the bluesemiconductor light emitting diode.

The manufacturing method or structure of the display device using thesemiconductor light emitting diode described above may be modified andimplemented in various forms. For example, a vertical semiconductorlight emitting diode may be applied as the display device describedabove. Hereinafter, a vertical structure will be described withreference to FIGS. 5 and 6.

In addition, in the modifications or embodiments described below, theidentical or similar reference numerals are assigned to the structuresidentical to or similar to the previous examples, and the descriptionsthereof are replaced with the first description.

FIG. 7 is a perspective view showing a display device using asemiconductor light emitting diode according to another embodiment ofthe present disclosure, FIG. 8 is a cross-sectional view taken alongline D-D of FIG. 7, and FIG. 9 is a conceptual diagram showing avertical semiconductor light emitting diode of FIG. 8.

Referring to the drawings, the display device may be a display deviceusing a passive matrix (PM) type vertical semiconductor light emittingdiode.

The display device includes a substrate 210, a first electrode 220, aconductive adhesive layer 230, a second electrode 240, and a pluralityof semiconductor light emitting diodes 250.

The substrate 210 is a wiring substrate on which the first electrode 220is disposed, and may include polyimide (PI) in order to implement aflexible display device. In addition, any insulating and flexiblematerials may be used.

The first electrode 220 is located on the substrate 210 and may beformed as a bar-shaped electrode elongated in one direction. The firstelectrode 220 may serve as a data electrode.

The conductive adhesive layer 230 is formed on the substrate 210 onwhich the first electrode 220 is located. Like the display device towhich the flip-chip type light emitting diode is applied, the conductiveadhesive layer 230 may be an anisotropy conductive film (ACF), ananisotropy conductive paste, a solution containing conductive particles,or the like. However, in the present embodiment as well, a case in whichthe conductive adhesive layer 230 is implemented by the anisotropyconductive film is exemplified.

When the semiconductor light emitting diode 250 is connected by applyingheat and pressure after placing the anisotropy conductive film in astate in which the first electrode 220 is located on the substrate 210,the semiconductor light emitting diode 250 is electrically connected tothe first electrode 220. In this case, the semiconductor light emittingdiode 250 is preferably disposed on the first electrode 220.

The electrical connection occurs because, as described above, when heatand pressure are applied to the anisotropy conductive film, theanisotropy conductive film has partial conductivity in the thicknessdirection. Therefore, the anisotropy conductive film is divided into aconductive portion 231 and a non-conductive portion 232 in the thicknessdirection.

In addition, since the anisotropy conductive film contains an adhesivecomponent, the conductive adhesive layer 230 implements not onlyelectrical connection but also mechanical bonding between thesemiconductor light emitting diode 250 and the first electrode 220.

As such, the semiconductor light emitting diode 150 is located on theconductive adhesive layer 130 to constitute the sub-pixel in the displaydevice. Since the semiconductor light emitting diodes 150 has excellentluminance, individual sub-pixels can be configured even with a smallsize. The size of the individual semiconductor light emitting diode 150may be a rectangular or square diode, of which the size of one side is80 μm or less. In the case of the rectangle diode, the size may be 20×80μm or less.

The semiconductor light emitting diode 250 may have a verticalstructure.

A plurality of second electrodes 240 are disposed between the verticalsemiconductor light emitting diodes 250 in a direction crossing thelength direction of the first electrode 220 and electrically connectedto the vertical semiconductor light emitting diodes 250, respectively.

Referring to FIG. 9, the vertical semiconductor light emitting diodeincludes a p-type electrode 256, a p-type semiconductor layer 255 formedon the p-type electrode 256, an active layer 254 formed on the p-typesemiconductor layer 255, an n-type semiconductor layer 253 formed on theactive layer 254, and an n-type electrode 252 formed on the n-typesemiconductor layer 253. In this case, the p-type electrode 256 locatedat a lower portion may be electrically connected to the first electrode220 by the conductive adhesive layer 230, and the n-type electrode 252located at an upper portion may be electrically connected to the secondelectrode 240 to be described later. The vertical semiconductor lightemitting diode 250 has a great advantage of reducing the chip sizebecause electrodes can be arranged above and below.

Referring to FIG. 8, a phosphor layer 280 may be formed on one surfaceof the semiconductor light emitting diode 250. For example, thesemiconductor light emitting diode 250 is a blue semiconductor lightemitting diode 251 that emits blue (B) light, and a phosphor layer 280for converting the blue (B) light into a color of a sub-pixel may beincluded. In this case, the phosphor layer 280 may be a red phosphor 281or a green phosphor 282 constituting an individual pixel.

That is, the red phosphor 281 capable of converting blue (B) light intored (R) light may be stacked on the blue semiconductor light emittingdiode 251 at a position constituting a red sub-pixel, and the greenphosphor 282 capable of converting blue (B) light into green (G) lightmay be stacked on the blue semiconductor light emitting diode 251 at aposition constituting a green sub-pixel. In addition, the bluesemiconductor light emitting diode 251 may be used alone at the portionconstituting the blue sub-pixel. In this case, red (R), green (G), andblue (B) sub-pixels may constitute one pixel.

However, the present disclosure is not necessarily limited thereto, andas described above in the display device to which the flip-chip typelight emitting diode is applied, other structures for implementing blue,red, and green colors may be applied.

In the present embodiment, the second electrode 240 is located betweenthe semiconductor light emitting diodes 250 and electrically connectedto the semiconductor light emitting diodes 250. For example, thesemiconductor light emitting diodes 250 may be arranged in a pluralityof columns, and the second electrodes 240 may be located between thecolumns of the semiconductor light emitting diodes 250.

Since the distance between the semiconductor light emitting diodes 250constituting the individual pixels is sufficiently large, the secondelectrodes 240 may be located between the semiconductor light emittingdiodes 250.

The second electrode 240 may be formed as a bar-shaped electrodeelongated in one direction, and may be disposed in a directionperpendicular to the first electrode 220.

In addition, the second electrode 240 and the semiconductor lightemitting diode 250 may be electrically connected to each other by anelectrode protruding from the second electrode 240. Specifically, theconnection electrode may be the n-type electrode 252 of thesemiconductor light emitting diode 250. For example, the n-typeelectrode 252 is formed as an ohmic electrode for ohmic contact, and thesecond electrode 240 covers at least a portion of the ohmic electrode byprinting or deposition. Therefore, the second electrode 240 and then-type electrode 252 of the semiconductor light emitting diode 250 maybe electrically connected to each other.

As shown, the second electrode 240 may be located on the conductiveadhesive layer 230. If necessary, a transparent insulating layer (notshown) including silicon oxide (SiOx) or the like may be formed on thesubstrate 210 on which the semiconductor light emitting diode 250 isformed. When the second electrode 240 is located after the transparentinsulating layer is formed, the second electrode 240 is located on thetransparent insulating layer. In addition, the second electrode 240 maybe formed spaced apart from the conductive adhesive layer 230 or thetransparent insulating layer.

When a transparent electrode such as indium tin oxide (ITO) is used inlocating the second electrode 240 on the semiconductor light emittingdiode 250, the ITO material has a problem in that it has poor adhesionto the n-type semiconductor layer 253. Therefore, the present disclosurehas an advantage of not using a transparent electrode such as ITO bylocating the second electrode 240 between the semiconductor lightemitting diodes 250. Therefore, the light extraction efficiency can beimproved by using a conductive material having good adhesion to then-type semiconductor layer 253 as a horizontal electrode without beinglimited by the selection of the transparent material.

Referring to the drawings, partition walls 290 may be located betweenthe semiconductor light emitting diodes 250. The partition walls 290 maybe disposed between the vertical semiconductor light emitting diodes 250in order to isolate the semiconductor light emitting diodes 250constituting individual pixels. In this case, the partition walls 290may serve to separate the individual sub-pixels from each other, and maybe integrally formed with the conductive adhesive layer 230. Forexample, since the semiconductor light emitting diode 250 is insertedinto the anisotropy conductive film, the base member of the anisotropyconductive film may form the partition wall 290.

In addition, when the base member of the anisotropy conductive film isblack, the partition wall 290 may have reflective properties and acontrast ratio may be increased, even without a separate blackinsulator.

As another example, the partition wall 290 may be separately providedwith a reflective partition wall. The partition wall 290 may include ablack or white insulator depending on the purpose of the display device.

If the second electrode 240 is directly located on the conductiveadhesive layer 230 between the semiconductor light emitting diodes 250,the partition wall 290 may be located between the vertical semiconductorlight emitting diode 250 and the second electrode 240. Therefore,individual sub-pixels can be configured with a small size by using thesemiconductor light emitting diode 250. Since the distance between thesemiconductor light emitting diodes 250 is relatively large, the secondelectrode 240 can be located between the semiconductor light emittingdiodes 250. Therefore, there is an effect that a flexible display devicehaving HD image quality can be implemented.

In addition, a black matrix 291 may be disposed between the phosphors inorder to improve contrast.

As described above, the semiconductor light emitting diode 250 islocated on the conductive adhesive layer 230 to constitute individualpixels in the display device. Since the semiconductor light emittingdiodes 250 has excellent luminance, individual sub-pixels can beconfigured even with a small size. Therefore, a full-color display inwhich red (R), green (G), and blue (B) sub-pixels constitute one pixelcan be implemented by the semiconductor light emitting diodes 250.

Hereinafter, a display device using a semiconductor light emitting diode(hereinafter, ‘display device’) having a hole having a structure forefficiently collecting light emitted from the semiconductor lightemitting diode to a front surface of a panel will be described in moredetail with reference to FIGS. 10 to 14.

FIG. 10 is a view showing a vertical cross-section of a hole in whichthe semiconductor light emitting diode is disposed, according to anembodiment of the present disclosure, FIG. 11 is a view showing avertical cross-section of a hole in which the semiconductor lightemitting diode is disposed, according to another embodiment of thepresent disclosure, FIGS. 12a to 12e are views showing variousembodiments of the hole shown in FIG. 11, FIG. 13 is a view showingproblems that may occur in a reflective layer structure according to anembodiment of the present disclosure, and FIG. 14 is a view showing astructure of a reflective layer according to an embodiment of thepresent disclosure.

A display device 1000 according to an embodiment of the presentdisclosure may include a substrate 1010 and a plurality of semiconductorlight emitting diodes 1020 disposed on the substrate 1010.

The substrate 1010 may be made of an insulating transparent material oran insulating opaque material. The substrate 1010 may include glass orpolyimide (PI) in order to implement flexible performance.

The semiconductor light emitting diode 1020 disposed on the substrate1010 may be a micro semiconductor light emitting diode, of which oneside has a scale of 1 to 100 μm. For example, the semiconductor lightemitting diode 1020 shown in FIG. 1 may be used.

Only a blue semiconductor light emitting diode that emits blue light maybe disposed on the substrate 1010, or a green semiconductor lightemitting diode that emits green light and/or a red semiconductor lightemitting diode that emits red light may be disposed on the substrate1010 together with the blue semiconductor light emitting diode. Each ofthe semiconductor light emitting diode 1020 may further include, as asub-pixel, a phosphor layer (not shown) that converts the color of theemitted light on the semiconductor light emitting diode 1020 asnecessary to form one pixel including red (R), green (G), and blue (B).

In the present embodiment, a separate electrode (not shown) for wiringis not disposed on the substrate 1010 by a reflective layer 1060 to bedescribed later, and the electrode may be provided outside the substrate1010 so as to be electrically connected to the electrode layer of thesemiconductor light emitting diode 1020 through a method such as metalwiring. That is, in the present embodiment, the semiconductor lightemitting diode 1020 may be provided on the substrate 1010 so that theelectrode layer faces the front surface of the panel, and may beconnected to an external electrode above the semiconductor lightemitting diode 1020.

On the other hand, a planarization layer 1040 serving as a protectivelayer of the substrate 1010 may be stacked on the substrate 1010.Specifically, the planarization layer 1040 may be stacked on thesubstrate 1010 while forming a hole 1030 that is an area in which thesemiconductor light emitting diode 1020 is disposed. The planarizationlayer 1040 may be made of an insulating material, for example, aphotoresist, an optical polymer material, or other industrial plasticmaterial.

A black matrix (BM) (not shown) for implementing black of the panel maybe further provided on the upper surface of the planarization layer1040. The black matrix may be formed only in a region in which a secondportion 1060 d extending to the upper surface of the planarization layer1040 as a portion of the reflective layer 1060 to be described later isnot formed, or may be formed to cover the second portion 1060 d. Theblack matrix (not shown) has an effect of improving contrast.

On the other hand, the structure of the hole 1030 can be confirmedthrough FIG. 10. Referring to FIG. 10, the hole 1030 is a region formedby the planarization layer 1040, and the semiconductor light emittingdiode 1050 may be disposed inside the hole 1030. The hole 1030 may beformed to have a width and a height greater than those of thesemiconductor light emitting diode 1020 disposed inside the hole 1030.In addition, the cross-sectional shape (vertical cross-section) of thehole 1030 cut in a plane perpendicular to the substrate 1010 may have abilaterally symmetrical structure.

The hole 1030 may be filled with a light-transmitting layer 1050. Thelight-transmitting layer 1050 may be made of a light-transmittingmaterial having high transmittance in the visible ray region, and anepoxy-based photoresist, poly dimethyl siloxane (PDMS), resin, or thelike may be used as the light-transmitting material. By filling theperipheral region of the semiconductor light emitting diode 1020 withthe light-transmitting layer 1050, reflection or total reflection oflight emitted to the side of the semiconductor light emitting diode 1020may be induced to improve light extraction efficiency.

In addition, the hole 1030 may include a reflective layer 1060 formedalong at least the inner surface of the hole 1030. Here, the innersurface of the hole 1030 may refer to one surface of the substrate 1010and the planarization layer 1040 facing the inside of the hole as shownin FIG. 10. Specifically, the inner surface of the hole 1030 may referto the upper surface of the substrate 1010 and the side surface of theplanarization layer 1040. The reflective layer 1060 is formed along atleast one surface of the substrate 1010 and the planarization layer 1040defining the inner surface of the hole 1030, so that the luminousefficiency of the semiconductor light emitting diode 1020 is improved byreflecting the light leaking to the back (substrate side) and/or side(planarization layer side) of the semiconductor light emitting diode1020 toward the front of the panel.

In addition, the hole 1030 may be formed so that the width thereofexpands as the distance from the substrate 1010 increases in order toincrease the light collection efficiency by the reflective layer 1060.As shown in FIG. 12, the hole 1030 may be formed in variously modifiedforms within a range in which the vertical cross-section has abilaterally symmetric structure. The related descriptions will be givenlater, and the reflective layer 1060 of the present disclosure will befirst described in detail.

According to an embodiment of the present disclosure, the reflectivelayer 1060 may be formed to a predetermined thickness along at least onesurface of the substrate 1010 and the planarization layer 1040 formingthe inner surface of the hole 1030. Preferably, the reflective layer1060 may be formed to a thickness of at least 30 nm in order to preventlight leakage.

The reflective layer 1060 may be formed so that a portion formed alongone surface of the substrate 1010 among the inner surfaces of the hole1030 (hereinafter, referred to as a ‘lower reflective layer 1060 a’)have a thickness greater than a portion formed along one surface of theplanarization layer 1040 (hereinafter, referred to as a ‘side reflectivelayer 1060 b’). That is, the reflective layer 1060 may be formed so thatthe lower reflective layer 1060 a has a thickness greater than that ofthe side reflective layer 1060 b, thereby more effectively preventinglight leakage to the rear surface of the panel.

On the other hand, the reflective layer 1060 may further include a firstportion 1060 c extending along at least a portion of an interfacebetween the substrate 1010 and the planarization layer 1040 and/or asecond portion 1060 d extending to cover at least a portion of the uppersurface of the planarization layer 1040. At this time, the first portion1060 c and the second portion 1060 d are portions extending from thelower reflective layer 1060 a and the side reflective layer 1060 b,respectively, and may complement the functions of the lower reflectivelayer 1060 a and the side reflective layer 1060 b.

For example, the first portion 1060 c and the second portion 1060 d mayuniformly reflect the emitted light to the front surface of the paneleven when the position of the semiconductor light emitting diode 1020disposed inside the hole 1030 is not constant. That is, in the processof assembling the semiconductor light emitting diode 1020, there is aneffect that the light collection efficiency can be maintained bysupplementing the positional accuracy of the semiconductor lightemitting diode 1020.

On the other hand, when the reflective layer 1060 is formed, as shown inFIG. 13, the lower reflective layer 1060 a and the side reflective layer1060 b may be discontinuously formed (defective point 1) or the sidereflective layer 1060 b may be omitted in a portion of the planarizationlayer 1040 (defective point 2), thus causing light leaks through thedefective points. In this regard, by additionally forming the firstportion 1060 c extending from the lower reflective layer 1060 a, thereis no risk of defect points (align margin) and light leakage can beprepared.

When the second portion 1060 d is additionally formed, it is possible toprevent crosstalk with the semiconductor light emitting diode 1020disposed in an adjacent hole. Light refracted from the upper portion ofthe hole 1030 toward the hole 1030 is re-reflected to the front of thepanel, thereby improving light extraction efficiency. On the other hand,in the case of a structure in which the semiconductor light emittingdiode 1020 and the wiring electrode are connected to each other at theupper portion of the hole 1030, the second portion 1060 d is preferablyformed only at a portion of the upper surface of the planarization layer1040.

Referring to FIG. 14, the reflective layer 1060 includes asingle-layered or multi-layered metal thin film layer 1061, and mayoptionally include a protective layer 1062 for insulation andanti-oxidation on the upper portion of the metal thin film layer 1061.

The metal thin film layer 1061 may have a single-layered ormulti-layered structure made of a metal thin film having goodreflectance. Preferably, the metal thin film layer 1061 may include oneof titanium (Ti), aluminum (Al), silver (Ag), chromium (Cr), molybdenum(Mo), and platinum (Pt), or any combination thereof.

Specifically, the metal thin film layer 1061 may have a single-layeredstructure including a single metal thin film having good reflectivity ora multi-layered structure formed by depositing two or more metal thinfilms having good reflectivity. For example, the metal thin film layer1061 may have a single-layered structure including a single metal thinfilm such as Ti, Al, or Ag, or a multi-layered structure in which two ormore metal thin films such as Ti/Al, Ti/Al/Ti, Mo/Al, Mo/Al/Mo, orMo/Al/Ti are stacked.

In the case of the metal thin film layer 1061 having the multi-layeredstructure, a metal such as Ti, Cr, Mo, or Pt may be optionally includedfor adhesion (or adhesive strength) between adjacent metal thin films.

In addition, each of the metal thin film layers 1061 a, 1061 b, and 1061c may be formed to a thickness of several nm to several tens of nm toform the reflective layer 1060 having a total thickness of 30 nm ormore.

The protective layer 1062 is a thin film made of an inorganic materialhaving light transmittance and insulating properties, such as SiO2 orSiNx. The protective layer 1062 is formed on the metal thin film layer1061 to function as an insulating film or an anti-oxidation film of themetal thin film layer 1061.

On the other hand, when the upper metal thin film layer 1061 is made ofTi or Al, TiO2 or Al2O3 layers that can perform substantially the samefunction as the protective film layer 1062 are formed on the surface.Therefore, the reflective layer 1060 may not include a separateprotective layer 1062 for the metal thin film layer 1061.

On the other hand, as described above, the lower reflective layer 1060 amay be formed to have a thickness greater than that of the sidereflective layer 1060 b. For example, the lower reflective layer 1060 amay have a thickness different from that of the side reflective layer1060 b by further including at least one layer (the metal thin filmlayer 1061 and/or the protective layer 1062) as compared with the sidereflective layer 1060 b. Alternatively, the lower reflective layer 1060a and the side reflective layer 1060 b may have the same structure, butmay have different thicknesses by varying the thickness of each layerconstituting the structure. As such, the lower reflective layer 1060 amay be formed to have a thickness greater than that of the sidereflective layer 1060 b, and may be formed to have the same thickness asthat of at least the side reflective layer 1060 b.

Next, various embodiments of the hole 1030 according to an embodiment ofthe present disclosure will be described with reference to FIG. 12.

As shown in FIG. 11, the hole 1030 of the present disclosure may beformed so that the width thereof expands as the distance from thesubstrate 1010 increases. Specifically, the planarization layer 1040defining the side surface of the hole 1030 may be inclined in adirection to expand the width of the hole 1030 as the distance from thesubstrate 1010 increases. The width of the hole 1030 may increase as thedistance from the substrate 1010 increases due to the inclinationdefined by the planarization layer 1040. In addition, thecross-sectional shape (vertical cross-section) of the hole 1030 cut in aplane perpendicular to the substrate 1010 may have a bilaterallysymmetrical structure. Such a structure of the hole 1030 can improve thelight collection efficiency of the light emitted from the semiconductorlight emitting diode 1020 disposed inside the hole 1030. In particular,the structure of the hole 1030 causes the light leaking to the side ofthe semiconductor light emitting diode 1020 to be directed toward thefront of the panel.

Under the above-described structure, the hole 1030 may include aplurality of regions 1030 a, 1030 b, and 1030 c partitioned based on anarbitrary height as shown in FIGS. 12b to 12 e.

The arbitrary height that is the reference for partitioning the regionsof the hole 1030 may be determined by the shape, thickness, structure,and the like of the semiconductor light emitting diode 1020 disposedinside the hole 1030. Specifically, the height that is the reference forpartitioning the regions of the hole 1030 may be different according towhether the semiconductor light emitting diode 1020 disposed inside thehole 1030 is a flip-chip type or a vertical type, the thickness of thesemiconductor light emitting diode 1020 in the height direction, or thelike. In addition, at the height, the planarization layer 1040 mayextend in a horizontal direction while expanding the width of the hole1030.

The plurality of regions 1030 a, 1030 b, and 1030 c may be formed tohave the same height H in the height direction (FIGS. 12b and 12d ), orthe thicknesses H of at least one region in the height direction may beformed to be different from the thickness H of another region in theheight direction (FIGS. 12c and 12e ).

On the other hand, the planarization layer 1040 may include a pluralityof layers 1040 a, 1040 b, and 1040 c stacked in the height direction ofthe hole 1030. Each of the layers 1040 a, 1040 b, and 1040 c may be madeof any one of the materials forming the planarization layer 1040. Thelayers 1040 a, 1040 b, and 1040 c may be made of the same material, orat least the adjacent layers may be made of different materials. In thelatter case, the planarization layer 1040 may be formed by depositing aplurality of layers.

In addition, the planarization layer 1040 may have a predetermined slope(or ‘inclination angle (A)’) with respect to the substrate 1010 or animaginary plane parallel to the substrate 1010. The slopes of theplanarization layers 1040 a, 1040 b, and 1040 c included in therespective regions may be equal to each other (FIGS. 12b and 12d ), orthe slope of the planarization layer included in at least one region maybe different from the slope of the planarization layer included inanother region (FIGS. 12c and 12e ). Here, the planarization layerincluded in a certain region may refer to the planarization layerdefining the side surface of the region (for example, the planarizationlayer 1040 a included in the first region 1030 a refers to theplanarization layer 1040 a defining the side surface of the first region1030 a). The planarization layer 1040 may be formed to have aninclination angle A of 20° or more and 90° or less with respect to thesubstrate 1010 or an imaginary plane parallel to the substrate 1010.

The thicknesses H of the plurality of regions 1030 a, 1030 b, and 1030 cin the height direction and the slopes of the planarization layers 1040a, 1040 b, and 1040 c included in the respective regions may be modifiedand implemented in various forms as shown in FIG. 11, considering thestructure and shape of the semiconductor light emitting diode 1020disposed inside the hole 1030 and the amount of light extracted to thefront of the panel.

On the other hand, the planarization layer 1040 and the reflective layer1060 defining the side surface of the hole 1030 according to the presentdisclosure may be formed by spin coating. By controlling a rotationspeed of a spin coater, the planarization layer 1040 and the reflectivelayer 1060 may be formed to be inclined, and the slope thereof may becontrolled. In addition, the planarization layer 1040 and the reflectivelayer 1060 may be formed by various known methods including slitcoating.

The hole 1030 according to the present disclosure may be formed invarious shapes (horizontal cross-section), including a rectangular shapeand a circular shape, which can collect the light emitted from thesemiconductor light emitting diode 1020 to the front surface of thepanel. Preferably, the hole 1030 may be formed in a circular shape. Inthis case, this is advantageous in terms of align margin in the processof aligning the position of the semiconductor light emitting diode 1020on the transfer substrate and the position of the hole 1030 formed inthe substrate 1010 so as to correspond to each other in order totransfer the semiconductor light emitting diode 1020 to the substrate1010.

The display device 1000 using the semiconductor light emitting diodeaccording to an embodiment of the present disclosure has an effect ofefficiently collecting light emitted from the semiconductor lightemitting diode 1020 to the front surface of the panel due to the shapeand structural characteristics of the hole 1030 in which thesemiconductor light emitting diode 1020 is disposed.

The display device 1000 using the semiconductor light emitting diodedescribed above can be applied not only to the passive matrix (PM) typesemiconductor light emitting diode, but also to the active matrix (AM)type semiconductor light emitting diode.

The present disclosure described above is not limited to theconfiguration and method of the embodiments described above, and all orpart of the embodiments may be selectively combined so that variousmodifications can be made.

1. A display device comprising: a semiconductor light emitting diodedisposed on a substrate; a planarization layer stacked on the substratewhile defining a hole that is a region in which the semiconductor lightemitting diode is disposed; a light-transmitting layer filling the hole;and a reflective layer disposed along at least one surface of thesubstrate and the planarization layer defining an inner surface of thehole, wherein the hole is disposed so that a width thereof expands as adistance from the substrate increases, and wherein the reflective layercomprises a first portion extending along at least a portion of aninterface between the substrate and the planarization layer.
 2. Thedisplay device of claim 1, wherein a cross-sectional shape of the holehas a bilaterally symmetrical structure when cut in a planeperpendicular to the substrate.
 3. The display device of claim 1,wherein the hole includes a plurality of regions partitioned based onheight relative to the substrate, and wherein thicknesses of therespective plurality of regions in a height direction are equal to eachother.
 4. The display device of claim 1, wherein the planarization layeris inclined to expand the width of the hole as the distance from thesubstrate increases.
 5. The display device of claim 4, wherein the holeincludes a plurality of regions partitioned based on height relative tothe substrate, and wherein slopes of the planarization layer included inthe respective plurality of regions with respect to the substrate or animaginary plane parallel to the substrate are equal to each other. 6.The display device of claim 1, wherein the planarization layer includesa plurality of layers stacked in a height direction of the hole, and atleast adjacent layers of the planarization layer are made of differentmaterials.
 7. The display device of claim 1, wherein the reflectivelayer is disposed so that a portion formed along one surface of thesubstrate of the inner surface of the hole is thicker than a portionformed along one surface of the planarization layer of the inner surfaceof the hole.
 8. (canceled)
 9. The display device of claim 1, wherein thereflective layer further comprises a second portion extending to coverat least a portion of an upper surface of the planarization layer. 10.The display device of claim 1, wherein the reflective layer comprises ametal thin film layer having a single-layered or multi-layeredstructure, and wherein the metal thin film layer is made of one oftitanium (Ti), aluminum (Al), silver (Ag), chromium (Cr), molybdenum(Mo), and platinum (Pt), or any combination thereof, and is formed to athickness of at least 30 nm or more.
 11. The display device of claim 10,wherein the reflective layer further comprises a protective layer madeof SiO₂ or SiNx on the metal thin film layer.
 12. The display device ofclaim 1, wherein the hole has a circular horizontal cross-section. 13.The display device of claim 1, further comprising a black matrix on anupper surface of the planarization layer.
 14. The display device ofclaim 1, wherein the hole includes a plurality of regions partitionedbased on height relative to the substrate, and wherein a thickness of atleast one of the plurality of regions in a height direction is differentfrom a thickness of another region of the plurality regions in theheight direction.
 15. The display device of claim 4, wherein the holeincludes a plurality of regions partitioned based on height relative tothe substrate, and wherein a slope of the planarization layer includedin at least one of the plurality of regions with respect to thesubstrate or an imaginary plane parallel to the substrate is differentfrom a slope of the planarization layer included in another region ofthe plurality of regions.
 16. A display device comprising: aplanarization layer disposed on a substrate and defining a hole; asemiconductor light emitting diode disposed on the substrate anddisposed in the hole; and a reflective layer including a first portionand a second portion, the first portion disposed along an upper surfaceof the substrate and an inner side surface of the planarization layerdefining the hole, and the second portion extending from the firstportion and disposed along a portion of an interface between thesubstrate and the planarization layer.
 17. The display device of claim16, wherein the reflective layer further comprises a third portionextending from the first portion and disposed on an upper surface of theplanarization layer.
 18. The display device of claim 16, furthercomprising a light-transmitting layer disposed in the hole andsurrounding the semiconductor light emitting diode.
 19. The displaydevice of claim 18, wherein an upper surface of the light-transmittinglayer is disposed higher than an upper surface of the planarizationlayer.
 20. The display device of claim 16, wherein the inner sidesurface of the planarization layer is inclined to expand a width of thehole as a distance from the upper surface of the substrate increases.21. The display device of claim 20, wherein the planarization layerincludes a plurality of regions partitioned based on height, and whereina slope of the planarization layer included in at least one of theplurality of regions with respect to the upper surface of the substrateor an imaginary plane parallel to the upper surface of the substrate isdifferent from a slope of the planarization layer included in anotherregion of the plurality of regions.